1. Field of the Invention
The present invention relates to a method of manufacturing an expansion joint, and more particularly, to a method of manufacturing an expansion joint, which is used in a fixed-plate heat exchanger. The method of manufacturing the present invention can carry out shaping in the outer radial direction at room temperature, so that physical properties are not changed, thereby ensuring sufficient stability against internal pressure and stress caused by contraction, saving raw material and reducing manufacturing cost.
2. Description of the Related Art
FIG. 1 is a process view sequentially illustrating a conventional process of manufacturing an expansion joint. The conventional process of manufacturing an expansion joint includes a marking and cutting procedure S100 of marking raw material and cutting the raw material along the marking, a shaping procedure S110 of shaping the outside portion of a product according to a desired shape and dimensions using a spinning machine (lathe, a marking and cutting procedure S120 of marking the inside portion of the product, the outside portion of which is formed, and cutting the product along the marking, and a shaping procedure S130 of shaping the inside portion of the product according to a desired shape and dimension using the spinning machine. The conventional manufacturing process also includes a welding procedure S140. In the welding procedure, two products, which are obtained through the above procedures, are butted against each other and welded in the outer radial direction, so that an expansion joint is finally manufactured.
However, the conventional manufacturing process has drawbacks as follows: Since the rectangular raw material is circularly marked and cut so that the product can be manufactured at room temperature using a mold and a hydraulic press, the rest is discarded as scrap. This is a factor increasing the overall manufacturing cost. Since the outside portion is shaped by the spinning machine, it is possible only to process raw materials having a thickness up to 25 mm, thereby failing to ensure the reliability of the product. In particular, since marking is performed on the inside portion of the product in a state where the outside portion of the product is shaped, shaping time is increased and productivity is lowered. This increases the need for manpower and thus the labor cost, thereby raising the cost of the product.